1. Field of the Invention
This invention relates to the loading and transporting of litter patients aboard air-ambulances and more particularly to apparatus which permits synchronous elevating or lowering of the opposite ends of the litter and/or litter support, locking the litter and/or litter support in a selected position of elevation, and protecting the patient and litter support system in the event of aircraft down-crash or other large-scale forces.
2. Description of the Prior Art
Airborne ambulances in the prior art have utilized tiers of stationary litter racks and have no mechanism to assist in the loading of the upper racks, nor do they provide crash attenuation or a means of preventing differential motion of the litter during down-crash. Such systems require an unacceptable level of man power, physical effort and loading time which may be crucial during military medical evacuation under combat conditions. Examples of such prior art are U.S. Pat. Nos. 2,370,402, 2,473,364, 2,480,322 and 3,358,300. U.S. Pat. No. 3,605,136 provides for litter elevating and lowering but uses systems of chains, gears and worms, so is unacceptably heavy for aircraft use, and provides no force attenuation.
While force attenuation is known in seat constructions, such as in U.S. Pat. Nos. 3,968,863 and 4,027,905, the teaching for force attenuation in combination with synchronous litter supporting, elevating, lowering, and locking mechanism is believed to be novel.